Pavement and process of making the same.



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To all whom it may come i 4' Be it known that I, MICHAEL A. Porness, a citizen of. the United States, residing at Kansas City, in the county of Jackson and State of issouri, have invented new and 'useful Improvements in Pavements and Processes of Making the Same, of which the following is a specification.

This invention relates to paving material and, particularly, to paving material of the type covered by Letters Patent No. 1,008,433, granted to me November 14th, 1911, and consists in certain modifications of the process and product set forth therein.

An important object of this invention is to provide a pavement which is substantially free from mineral particles large enough to fracture in use, which has a homogeneous wear resisting and traflic supporting body, which will present a dense, smooth and malleable surface, which is tough, tenacious and of maximum durability,

which is practically free from voids, selfhealing and easy to repair and which will not ravel, rut wear into holes,'flow, creep, nor push into waves.

Other objects and advantages of the invention will be apparent during the course of the following description.

In an application for Letters Patentfiled by me April 21st, 1916, Serial No. 92,704, of which the present application is a division, I explained that I discovered in the use of the machine, disclosed in an application filed by me April 4, 1914, Serial No. 829,549, that the hard particles of dirty sand or gravel, decayed or soft stone, weathered rock and the like, are cleaned, polished and fractured, and in such condition serve as a valuable addition to the paving material set forth in my said patent. Application No. 92,704 covers the resulting paving material, that is to say, paving material composed of the earthy dust set forth in my said patent, or any kind' of mineral dust, intimately mixed with sufiicient asphalt to form a non-flowing matrix, in combination with a filler of clean stony particles, embedded-in and'separated from each other by to such matrix, which pavement differs from previously known pavements, in that the Specification Of Letters Patent. Patented Mar. 2'3, 191?. 7 Application filed September 15, 1916. Serial No. 120,873.

said filler is not the main wear resisting and tratlic supporting ingredient but those functions are performed by the mixture of asphalt and mineral dust. In such prior pavements the mineral aggregate of broken' proof the structure. In the type of pave-- ment of said application, the asphalt and dust together form a hard but malleable material which is the wear-resisting element of the roadway.

In the further course of experimentally treating such materials in the said machine, I found that the degree of pulverization of the rock, gravel, sand and the like, depends very largely upon the speed of rotation of the pulverizer and that it is possible, by speeding up the pulverizer, to reduce to dust a large proportion of such material and I discovered that the resulting mixture of stony dust thus obtained and earthy or clayey dust containing none or substantially free from the coarser particles will form a satisfactory wear resisting and traflic supporting mass when mixed in the proper proportions with a suitable binder, preferably asphalt. I also discovered that other stony material, such as sand, gravel, rock, and the like, reduced to an impalpable dust, even though free or substantially free from soil, loam, or clay dust, will also serve to' form a suitable pavement when mixed in the proper proportions with a suitable binder, such as asphalt. 4

My present invention, which is founded upon these discoveries, consists in a pavement comprising mechanically pulverized stony material of the nature of silica and silicates such as sand, gravel, pebbles and larger stones, rock, cinders and the like, in the form of impalpable dust, mixed in the proper proportions with-a suitable binder,

. preferably a bituminous binder such as asphalt, and in its preferred embodiment my the form of dust, and disintegrated earthy material, such as soil, loam, or clay and the like, in the form of dust, the stony material and the earthymaterial being mixed in the proper proportions with a suitable binder. The invention also comprises the process of making such pavement. In this material the dustlike particles are too small to permit such, if any, mechanical locking engagement or mutual support as is the case with compositions using mineral aggregates of the usual type.

particles are fractured andreduced to dustlike form and the lar er particles are given sharp corners and e ges observableunder the microscope, in contra-distinction to the round corners and edges which are possessed by ordinary sand and gravel which has been particles are and disintegrate,

fineness such that per cent. Wlll pass disintegrated by nature. The result of subjecting the mineral material to such pulverizing action, which is preferably carried on until substantially all of the particles are reduced .to the form of dust, is that in the product a natural grading of the various sized mineral particles takes place, that is to say, the spaces of voids between the larger filled by the very fine dust. This obviates. any necessity for artificial grading by weighing or measuring the materials of different sizes, to reduce the number of voids, a practice which is followed in the manufacture of ordinary asphalt pavements, made of sand, gravel orrock and asphalt. With such fine material there cannot, of course, be any voids of appreciable size between the particles; there cannot be the large voids which occur in the ordinary sand, roc and gravel asphalt pavements and which become filled with lakes of asphalt which soften and become displaced under heat.

The mineral material pulverized, or pulverized and disintegrated as described, is in the form of a very fine palpable dust, such that substantially all, or, at least, per cent. will pass through a 30 mesh screen and 50 per cent. will pass through a 100 mesh screen, but Iprefer to pulverize, or ulverize the material to a egree of througlra200' mesh screen.

-In mixing the mineral dust, either pulverized stony material alone or such material mixed with disintegrated earthy material,

with the customary practice in the paving with the binder I may proceed in accordance ('55 art. Preferably however the mineral dust is heated and dried, either before it is disintegrated or while it isbeing disintegrated, or afterward, and is then mixed in that condition with the hot binder such as asphalt. The disintegrated material may, however, be mixed in a moist condition with the binder, natural or artificial heat being applied during or after the mixing so that the binder will. penetrate the material as the moisture is driven oflI' and replace such moisture as more particularly described in an application filed by me April 11, 1916, Serial No. 90,391. The proportion of binder which should be used depends upon the fineness of the mineral dust employed, the finer such dust the greater the percentage of binder being required. It also depends upon whether stony dust alone is used or stony dust and earthy dust, the former requiring less binder than the latter. Where both are present the greater the proportion of earthy material the greater-percentage of binder required. In actual practice when using a bituminous binder, such as asphalt, I may employ from 12 to 25 per cent. of such binder. I prefer however to employ from 14 to 18 per cent. unless the material contains little or no earthy material, in which case I ordinarily employ from 12 to 16 per cent. of binder, the percentage set forth here in being calculated by weig t but in actual practice the amounts can be measured or weighed. A

In the use of my paving material it-is read upon a prepared base and tam or rolled on the surface to be aved. .Itmay however be p into bloc It will beunderstood that the term dust as herein employed refers to material of such an extreme degree of fineness that when dry it is'dust-like. The term is not intended to refer only to dry material but is intended to include wet, moist and dry material as well, providing it is of the degree of finenes that renders it dust-like when dry,

While I have particularly set forth the preferred degree of fineness of the mineral dust and the proportions of binder to be employed with such material, it is to be understood that these may be varied somewhat without departing from the spiritof my invention or the scope of the subj oined claims. It is also to be understood that-in some cases stony material can be obtained which is in the form of fine dust, and such dust can be used to produce a commercially practical pavement either alone or in conjunction with. dust made by disintegrating earthy material such as soil, loam, clay or the like.

Having described my invention, I claim:

1. A pavement composed of comminuted 190mm it stony material in the form of dust,

' 'mately mixed with a suitable binder, and

subjected to pressure.

2. A pavement composed of mechanically pulverized rock in the form of dust, intimately' mixed with a bituminous binder, and

spread and compacted upon the surface to and compacted upon the surface to be paved.

4:. A pavement composed of rock mechanically pulverized to dust, intimately mixed with not less than 12 per cent. and not more than 16 per cent. of asphalt, spread and compacted upon the surface to be aved.

5. A pavement composed o pulverized stony material such as stone, roc sand or gravel, substantially 40per cent. of which will pass a 200 mesh screen and approximately 90 per cent. of which will pass a 30 mesh screen, intimately mixed with bitumen, and spread and compacted upon the surface to be paved. p

6. A pavement composed of a, mixture of comminuted stony material and earthy material, both being in the form of dust, intimately mixed with a suitable binder and subjected to pressure.

7. A pavement composed of a mixture of comminuted stony material and earthy material, both bein in the form of a substantially dry dust, intimately mixed with a bituminous binder andspread and compacted upon the surface to be paved.

8. A pavement consisting of a tough and tenacious wear resisting and traflic supporting material, composed solely of a mixture of stony material such as sand, gravel, rock or stone and earthy material such as soil,

loam orclay, all pulverized to dust, and im- I pregnated with from 12 to 20 per cent. of asphalt.

9. The process of making a pavement which consists in mixing pulverized stony material, such as sand, gravel, or stone, and

- upon a pulverized earthy material, such as soil, loam or clay, substantially all in the form of fine dust, with notless than 12 per cent. of asphalt, spreading the mixture uniformly prepared. base and compacting it thereon.

10. The process of making a pavement,

pulverized to dust of such a fineness that at least 40 per cent. will pass a 200 mesh screen,

with asphalt, the proportion-of dust to asphalt'being not more than 88 to 12 and not less than 80 to 20, spreading the mixture uniformly upon a prepared base and compactin it thereon.

11. he procem of making a pavement,

material pulverized to under which consists in mim'ng stony and earthy dust to such a fine; ness that at least 40 per cent. wlll pass a 200 mesh screen, with asphalt, spreading the mixture uniformly upon a prepared base and compacting it thereon.

12. The rocess of producing paving material whic consists in pulverizing disintegrated rock, stone, gravel, or sand to such a degree of fineness that 4:0 per cent. will pass a 200 mesh screen, and impregnating the same with not less than 12 per cent. of

asphalt.

1 3. The process of producing paving materlal which consists in mechamcally comminutin stony and earthy material to dust, mixing 1t with spfii nonflowlng wear resisting and traffic supporting mass, spreading it uniformly upon a prepared base, and compacting it thereon. 14. The process of making a paving material, which consists in mixing pulverized stony material such as sand, gravel or stone and disintegrated earthy material such as soil, loam or clay, with not less than 12 per cent. of asphalt, and compacting the same ressure.

15. he process of makin terial, which consists in ta 'ng a natural earthy deposit, containing a large percentage of stony material, such as sand, gravel, or the like, reducing it to such a degree of fineness that substantially half the total amount will pass a 200 mesh screen and at least 90 per cent. will ass a 30 mesh screen, intimately mixing 1t in that condition with not less than 12 per cent. of asphalt, and compactin the same under pressure.

16. he process of makin a terial, which consists in p verlzing stony material such as sand, gravel, rock, and the like to that degree of fineness necessary for a thorou h incorporation therewith and even distribution therethrough of a liquefied bituminous binder, impregnating it with such binder and then compacting It by pressure whereby it becomes a tough malleable and paving ma- ,durable material adapted for the purpose verlzing friable stony materials to dust, and

a paving maincorporating the dust with a bihiminous binder and compacting the m ure.

19. The process of reducing a, homogeneous wear resisting su stance or paving or 5 other surfacing urposes, pulverizmg fria which consists in le earthy materials and soft stony particles to dust and mixing the dust with a bituminous bimler and compacting the mixture. 10 20. The process of pro dueing a homogeneous wear resisting substance for paving or other surfacmg purposes, whichcon'sists in simultaneously pulverizing friable stony- MICHAEL x. POPKESS. 

